Síntesis de nanopartículas de magnetita recubiertas de quitosano para la adsorción de cromo hexavalente

Abstract

The objective of this experimental work was to synthesize chitosan-coated magnetite nanoparticles for hexavalent chromium adsorption in aqueous solutions. The chitosan was obtained from the exoskeleton of the shrimp, and the nanoparticles were synthesized by chemical coprecipitation and coated with chitosan in an In-situ manner. Th synthesis of both chitosan and nanocomposite was verified by infrared spectroscopy and the size of the nanoparticles was determined from scanning electron microscopy. The adsorption capacity of hexavalent chromium was performed with the help of an experimental design of factorial type a*b*c, whose study factors were: initial concentration of the contaminant, contact time and temperature, and the quantification of hexavalent chromium was performed by UV-Visible spectroscopy. In such a way that chitosan-coated magnetite nanoparticles with an average diameter of 31.85 nm were obtained and the percentage of adsorption of hexavalent chromium using the nanoparticles, it was 99.70 %, at values of pH 3, 0.1 g of adsorbent, 5 mg/L of contaminant, temperature of 60 °C and 60 minutes of contact time. Moreover, from the experimental design it was estimated that the adsorption process followed a pseudo-second order kinetic model and the isotherm that best fit the process was Langmuir, and from it, a maximum adsorption of hexavalent chromium was feasible using magnetic nanoparticles coated with chitosan, obtaining greater adsorption capacity thanks to the chitosan coating, with protects and improves the adsorbent properties of the nanoparticles. If these results are reproducible in the future, it is recommended to preform adsorption tests by varying the agitation values and perform desorption processes of the nanoparticles.